[coppermtn]

I believe i am missing a vacuum line on my 87 astro. The defrost works great, but no heat out of the vents or floor. i just do not know which one or where it goes to? I have gotten rid of a lot of stuff, i can get pics. i also have the haynes manual. I'd like to get rid of as much of the a/c stufff as possible w/o affecting the heat/defrost. already have a bypass pulley installed for the a/c. any info woul dbe nice.

i cannot open the topic that chemist created further down the page at work, i'll check that out at home, i get denied for pornography reasons? whats in that post?

 

[guyonearth]

This is usually caused by the vacuum line being off or broken from the vacuum reservoir to the heater control panel. It can also be the line off at the control panel itself. When vacuum is off on these they default to defrost.